Knife blade switch and method of making the same



Oct. 6, 1931. C SCHUSTER 1,826,225

KNIFE BLADE SWITCH AND METHOD OF MAKING THE SAME Filed June 14, 1928 Patented Oct. 6, 1931 PATENT OFFIQE CARL SGI-IUSTER, F PITTSBURGH, PENNSYLVANIA KNIFE BLADE SWITCH AND METHOD OF MAKING THE SAME Application filed June 14,

My invention relates to electrical switchingequipment and more particularly to a knife blade switch and method of making the same.

Knife blade switches as heretofore constructed comprise a conventional hinge jaw constituted by a plurality of conducting jaw or stud members through which aclamping bolt extends. The clamping bolt also eX- tends through a plurality of separate blades which are connected to a common handle disposed at the ends of the blades remote from the hinge jaw. The turning movement of the blades about the clamping bolt tends to turn the clamping bolt against its nut and thereby loosen it with a resultant loss of good electrical contact.

In such switches, an effort is made to have the spacing between the flexible conducting strips constituting the jaws equal and to have the faces of the aw members constituting the hinge and break jaws in alinement in order to insure uniform contact between the blades and the jaws. Any irregularity in the pressure exerted by a jaw face against a blade face results in an imperfect electrical contact. An imperfect electrical contact is apt to result in an undesired heating of the n blades and aws and, in some cases, to result in sparking and the pitting of the contacting surfaces.

In applying a handle to a plurality of knife blades it has heretofore been customary to bring the ends of the blades into engagement with tightly fitting clamping devices or grooves on the handle. With tightly fitting clamping devices or grooyes, the plane of the blade is'determined in part by the plane of the devices or grooves where the blades are secured to the handle, and in part by the relation of that plane to the plane of the blade where the clamping bolt extends through it. The resultant configuration of N the blade does not necessarily conform to the planes defined by the faces of the hinge and break jaws. As a result, the contacting areas between the. blades and jaw faces are often of irregular shapes and sizes.

In an endeavor to remedy this difficulty, abrading material is sometimes placed be- 1928. Serial No. 285,271.

tween the jaw faces and the blades. The blades are then worked into and out of engagement with the break jaws until the faces of the jaws have been ground down to a considerable extent. However, the small 55 particles of abrading material produce scratches on the faces of the jaws and blades, which scratches produce an uneven electrical contact and likewise cause heating of the switch. The blades of such switches are not provided with lubricating grooves.

I provide a knife blade switch in which the clamping bolt for the hinge jaw is encased in a. tube of hard metal such as steel about which the blades turn to prevent theios clamping bolt from being turned during the movement of the switch blades. Lubricating grooves are provided between the con tacting faces of the blades and break jaw.

The blades are individually worked or seated into good electrical contact with their cooperating jaws with lubricating oil only present. This insures a firm uniform fit of the individual blades and jaws. Thereafter any convenient number of blades are brought into alinement and a handle, having portions i i that engage the ends of the blades without binding, is placed over the blade end without distorting the blades relative to their planes of engagement with the several jaws. Thereafter the handle is clamped to a securing means which is common to the several blades.

Certain of the features of the present in vention constitute improvements over the switches shown and described in my Patents 6 Nos. 1,086,622 and 1,086,623, issued February 10, 1914.

The accompanying drawings illustrate the present preferred embodiment of my invention, in which Q0 Figure 1 is an elevational View, partially in section, of a double pole switch constituted by a plurality of groups of blades and jaws;

Figure 2 is an end view of the switch illustrating the relation of the component parts thereof during assembly; and

Figure 3 is an edge view of a switch blade.

Referring to Figure 1, a knife blade switch comprises a plurality of groups of switch t ll blades 2, hinge aws a and break jaws 5. A common handle 6 is provided for engaging the ends of the blades 2 or the different groups. Fastening pins 7 extend through openings 8 near the ends of the blades. Clamping screws 9 extend through openings 10 in the yoke of the handle G and are hreaded into openings 11 in the pins 7. Any convenient number of groups of the blades 2 may be assembled in sideby-side relation and common fastening pins 7 passed ther through.

Each blade 2 is provided near the end oppo site the openings 8 with an opening 12 through which a tube 14:, preferably of hard metal such as steel, extends. The opposite faces of the blades are provided with diagonally extending grooves 13 for the passage of lubricating fluid.

Each of the hinge jaws l is made up of a plurality of studs or strips 15 of fierdble current conducting material. The studs are preferably of the jointless type snown and described in my afore-mentioned patents, al-

though it is to be understood that other p'PQS of studs may be employed, it desired. Each blade 2 is disposed between a pair of stuts 15. Spacing washers 16 are disposed between the pairs of studs engaging the several blades. The tube 14 extends through openings in the studs 15.

A clamping bolt 17 having a head 18 one end and threads 19 at the other end extends through openings 20 in spring washers 21 at the opposite sides of the iinge aw. A nut 22 is screwed onto the threaded end 19 of the clamping bolt for compressing the washers 21. As the washers 21 bear against the outer studs 15 oi": each jaw, the bolt 17 and washers 21 serve to compress the studs. washers and blades. thereby insuring good electrical contact. A the blades turn about the tube 14, frictional engagement between the blades 2 and the bolt 17 is eliminated, thereby preventing the unscrewing oil the bolt 17 and nut 22 due to the turning of tie switch blades about the hinge jaw. The break jaws 5 may be of any usual. construc tion, although I prefer to use the jointless studs described in my prior patents.

In assembling the switch. the several blades are mounted on the tube 14 with the clamping bolt 17. nut 22 and the washers 9.1 in place. The blades are individually worked about the hinge jaw t seat them into firm engagement with the hinge and break aws, using lubricating oil only, without any abrasive material, until a smooth and firm electrical engagement is had between the blades and jaws. A' iter the blades have been seated, a pair of pins 7 are inserted through the alined openings 8 of each group or pole. The handle 6 is placed over the ends of the blades with a sulliciently loose lit to prevent the binding of any of the blades with the walls of slots 24 in the yoke. After the blad and handle are in position, the screws 9 are inserted through the openings 10 in the yoke and threaded into the pins 7, thereby fastening the handle to the pins, as distinguished from directly fastening the yoke to the ends of the blades. By reason of the absence of an unyielding connection between the yoke and the ends oi the blades, the blades are not distorted from their plane of engagement with the break and hinge jaws by the handle.

By increasing the lengths of the pins 7 and the yoke of the handle (3, a single knife blade switch, comprising a plurality of groups of blades may be made for currents of large amperage.

lVhile I have illustrated and described the preferred. form of my invention, it may be understood that it may be otherwise cmbodied and practiced within the scope of the following claims.

I claim:

1. In a single-pole knife blade switch, a break jaw, a plurality oi blades having openings thcrethrough, a hinge jaw comprising plurality of studs having openings therethrough. a metal tube extending through the openings in the studs and blades, and clamping means extending through the tube.

2. In asingle-pole knife blade switch, a plurality of blades having openings near one end thereof. a break jaw, a hinge jaw comprising a plurality of spaced studs having openings therethrough and a. n'ietal tube extending through the openings in th blades and studs for constituting a hub for the blades, and securing means extending through the tube.

3. In a singlepole knife blade switch, a. plurality of blades having openings near one end thereof, break jaw, a hinge jaw comprising a plurality oi spaced studs having openings therethrough. a metal tube extending through the openings in the blades and studs for constituting a hub for the blades, securing means extending through the tube. and means co-operating with the studs and securing means for tensioning the studs into gagement with the blades.

41-. In a single-pole knife blade switch. a plurality of blades having: openings near one end thereof. a break jaw, a hinge jaw comprisii e a plurality of spaced studs having openin thercthrough metal tube extending through the openings in the blades and studs for constituting hub for the blades, securing means extending through the tube, and spring washers for tensioning the studs into engagement with the blades.

5. In a switch structure, a plurality of contact blades having openings therein, a pin extending through the several openings, a handle having its surface adapted to be seated lUi') firmly on the ends of the blades, and means for holding the handle tightly to the pin.

6. In a switch structure, a plurality of contact blades having openings therein, a clamp pin extending through the several openings, a handle seated on and firmly engaging the ends of the blades, and means traversing the handle and engaging said pin for clamping the handle to the pin.

7. In a knife blade switch, a plurality of blades, a hinge jaw for supporting the blades, a pin traversing the ends of the several blades, a switch handle seated on the ends of the blades, and means for drawing the handle and the pin together.

8. In a knife blade switch, a plurality of blades, a hinge jaw for supporting the blades, a common fastening device engaging the several blades, a switch handle adapted to engage the ends of the blades, and means for clamping the handle and fastening device together.

9. In a knife blade switch, a plurality of blades, a hinge jaw for supporting the blades, the blades having alined openings near one end thereof, a common securing device extending through the several openings, a switch handle having slots for the reception of the blades, and screws carried by the handle and threaded into the securing device for clamping the handle and securing device together.

10. In a single-pole knife blade switch, a base, a hinge jaw comprising a plurality of j ointless studs extending through the base, a clamping device for securing a contact blade to certain of the studs, and a metal sleeve sur rounding the clamping device and extending through alined openings in the blade and studs.

11. In a knife blade switch, a plurality of blades shiftably mounted in a hinge jaw comprising jointless studs, a handle for shifting said blades mounted on the ends thereof, a pin traversing said blades, and means for securin the handle to said pin whereby said handIe may be removed and said blades shift ed individually.

In testimony whereof I have hereunto set In hand.

y CARL SCHUSTER. 

